I hurt my foot yesterday on a long walk around Granton and Newhaven harbours. Think I've burst a blood vessel - Sore! So I'm sitting here watching TV and rereading some threads on the Forum. In the thread, here in Tech Talk, about Charlie's glowplugs there is reference to Air Tools and it set me to thinking. When I started in workshops it very quickly became apparent to me how useful compressed air can be and I immediately aspired to having it at home. Over the years, mostly constrained by money, I've achieved several solutions and explored the problem of air supply to the tools themselves. Would it be of interest to people to hear of this (I have illustrations too) or would it just be boring? Do let me know.

I recently aquired a compressor from my brother since he moved to NZ and have been considering piping the garage, I'm even considering sending a feed to the house for blowing water off the car after a wash (rather than dragging a chamois across the paint) and powering my model airbrush (with a reg of course).

Would love to hear your thoughts, don't haver too much though, I know what you're like

Eklipze3k said:

I recently aquired a compressor from my brother since he moved to NZ and have been considering piping the garage, I'm even considering sending a feed to the house for blowing water off the car after a wash (rather than dragging a chamois across the paint) and powering my model airbrush (with a reg of course).

Would love to hear your thoughts, don't haver too much though, I know what you're like

Click to expand...

Thanks Eklipze. I'm afraid a certain amount of havering comes free with me. But, if I do this, I'll try to control myself.

I would never ever claim to be a compressor expert but I do own one and there are some basic facts/factors that define an air compressor's ability/performance:

1) Pressure - PSI - BAR
2) Flow Rate - cfm (cubic feet per minute) - other volume per minute ratings
3) Air Tank Volume / Reserve

All three of these combine to make a the ideal compressor for a specific or range of jobs/applications.

If I replace the three above factors with:

a) Force
b) Rate of force application over time = power
c) Ability to sustain a) and b) over longer duration cycles

then one can readily align and understand what compressor performance one ideally requires for a given task/application.

If cost and size were not a limiting factor then you would go for 100% on all three basic performance measurements.

On the other hand if tyre, air bed, similar inflation was you application then good pressure and low air flow and low reserve would be fine. A simple cheap compressor.

If you want to drive garage power tools then good pressure, good glow rate/power and sustained ability.

If you are looking at using any air power tool/paint gun etc. the check the required PSI (pressure) and air flow rate required for correct operation.

Paint guns are a good example of diverse requirements. A small gravity fed paint gun is easy on PSI and flow rate. A suction paint gun is OK on PSI but requires a good/excellent air flow rate.

For general home usage then a compressor with a 5 to 10 litre air tank is about the minimum you can get away with. The bigger the better but then space, cost, and price to performance/usage comes into effect.

Pugglt Auld Jock said:

Thanks Eklipze. I'm afraid a certain amount of havering comes free with me. But, if I do this, I'll try to control myself.

Click to expand...

OK here we go. - As many will know a ready supply of compressed air when working on cars, bikes, machinery in general, is a very handy thing to have. Blowing the road grit out of spark plug recesses prior to removal, clearing carburetor jets, etc, etc. Early on I made do with a large old foot pump, a yard or so of flexible pipe and an old nozzle to give the jet. It worked quite well for the sort of thing described above as I could pump with my foot leaving one hand free to direct the jet and the other for manipulation. Then I got interested in spray painting. Can't do that without a compressor and I couldn't afford one.

Around that time, maybe 35 years ago, I was driving along, not far from home, passing the small body parts factor where I bought Panels/paint etc. Sitting on the pavement outside his shop was a rather unusual compressor. Knowing the staff quite well I popped my head round the door and asked what it was doing out there. "It's broke pal. - It's going to the scrapie as soon as the van gets back from deliveries". Could I have it? OK it'll save us a trip, but it's very old and doesn't pump. It took two of us to lift it into the back of my DAF 33 van and took the suspension down onto the bump stops, but I got it home without incident. It's biggest problem was that one of the "poppet" valve return springs was broken so it couldn't pump and it needed a new ball race on the pulley end of the electric motor. My local engineering supplies people, Forth Engineering, came up trumps on both items and, with a fresh sump of compressor oil, it ran whenever I needed it for roughly the next 25/30 years.

Here's a picture of my old "friend" just before I sold him.



I bought an SIP spray gun and resprayed the DAF! nearly asphyxiating myself with the fumes (cellulose in those days). The big drawback, which, in my ignorance I knew nothing about, is that you need lots of air to spray paint and my "pal" was a low capacity single cylinder device. It took around 15 to 20 minutes to bring that air receiver up to 100psi, so I could get only a few minutes spraying and then wait for 5 minutes or so till the pressure built up again. Around that time I bought my Clarke "windy" gun but hardly used it as it would only give one good burst before expiring asthmatically! The one thing I really liked about it was that it sounded like the single cylinder Field Marshal tractor I sometimes drove on the farm next door when I lived at home - Pock, Pock, Pock, Pock!

About 4 years ago I decided to treat myself to a compressor that could properly power the various air tools I'd accumulated over the years I'd thought a £300 budget would cover it and had "negotiated" this with Mrs Jock. I wanted a 50 litre or bigger receiver and I found that I could buy a direct coupled (motor and compressor in one unit) for that but when I found out how noisy and high revving they are I didn't feel I could subject my neighbours to it especially after my old quiet running machine. Then, quite by chance, I came across the Wolf Dakota being sold by UKHS. Direct drive, slow running, 3HP, 14CFU (is that free air though? the windy gun needs about 9) 90 litre receiver and MUCH less money than Clarke or similar. Spent about a week looking into it and found out that most of these small units are made in china. In fact when you start looking closely at them they are all pretty similar (bet a lot of them are made by the same people?). Ah well, you can't afford anything "better" Jock so it's either this or nowt! So, feeling very nervous that I might be making a big (expensive) mistake, I ordered it. Here it is being unbox



It's mounted on wheels so is very easy to move. Surprisingly it doesn't move around when running and it fits beautifully into the space where the old machine used to live.



It's advertised as suitable to run on a 13amp supply. Well yes it does BUT, only if it's a fused supply. My garage is on an RCD, the house is fused, it trips the RCD every time but runs happily for hours on the socket in the utility room. My friend's son (electrician) has explained it's all to do with the Capacitive starter. He also says it probably just about blows the fuse each time it starts but will only pull about half that when running. He's going to wire in a "proper" supply for me when he's not busy but it's been running like this, on an occasional use basis for a couple of years now. Also worth mentioning that, although not silent by any stretch of the imagination it is as quiet running as the old machine and MUCH MUCH quieter than a direct coupled machine. I notice SGS seem to be selling the same machine until recently at twice the price but now, on an offer, very slightly cheaper than UKHS.

Now to what might interest you Eclipze. What to do about plumbing? My first thought was to go for hard lines fixed to the wall ('cos that's the way I've always seen it done.) It was at this time I bought the CP 7748 and I got very interested in maximising air supply. Until then my couplings were all the old PCL type with 1/4" bore rubber hosing but the wolf came with the new metric type and I immediately noticed they have a considerably bigger bore. OOOH, more air! - PCL on the left metric on right.



The metric fittings were not so easy to source then so I popped round to Pirtek to have a chat. "The man" went away into his store to get what I wanted leaving me to wander round the small showroom. In the corner behind the door was a large coil of 1/2" bore rubber air hose. Hmm. If I use that it will give me much more flexibility than having it hard plumbed to the wall? (What with the compressor being wheel mounted and all). "What's with the hose behind the door then?" I asked him on his return. It's scrap, was run over by a forklift so can't be certified. I had a good look at it and could see the wheel marks in one small length only. Can I have it? "No, but I'll take silly money for it" I snapped it up and got about 40 feet of usable hose. It's plumbed directly into the end of the receiver via an isolating tap as you can see in the third image above. This leaves the built in regulated supply for connecting my air pistol.

This hose is long enough to let me reach not only anywhere in the garage but also to anywhere on the car when parked on the hard standing outside the garage door. Two drawbacks though. Being a large diameter it's not as flexible as a smaller hose and it has no pressure regulation - doesn't half make the Windy gun go though! Normally I have the compressor at the back of the workshop with the hose along the wall held in place by canvas slings. The last 20 foot is coiled just inside the garage door. When the pressure needs to be controlled I have a pressure regulator/moisture separator which the hose plugs into and a 3/8" bore hose (for better flexibility) leading off to the device (spray/underseal/cavity injection gun etc). I have this mounted on a separate "caddy" which also has storage space for appliances.



You can see the larger hose going in on the left and the smaller coming out on the right.



The old 1/4" bore hose now sees duty on my tyre inflator.

So you'd think I'd be happy now with my lovely compressor, powerful new air gun and other devices all working well. But it suddenly occurred to me that I've got some pretty long runs of hose going on here and long hoses equal pressure drop, don't they? So I decided to see if I could find a way of checking the actual pressure acting on the gun at the end of the hose. I took a selection of coupling pieces, buffed the rubber off the outside of a tyre valve and J B welded it to a hole I drilled in the side and ended up with this



Attaching my tyre inflator gauge to it let me monitor what was actually arriving at the gun inlet (Manufacturer recommended maximum of 90 psi)



Experimenting with this was very interesting and revealing. The compressor came with it's regulator set at 100 psi but the manual states it can cope with up to 150 psi (albeit, I suspect, with reduced life) I decided to increase it to 125 psi as I won't be putting the hours on it. With the CP connected to the 1/2" hose - so no regulator in circuit - it's an absolute hooligan! I can hardly think of anything on a car it wouldn't remove! Checking the pressure reveals barely a 5 psi drop at the gun when on full throttle! Now plug the 3/8" hose into the end of the !/2" and there is around 10 to 12 psi lost. Take off the 3/8 and plug in the 1/4" and right away the gun turns into a whimp. Pressure lost? not far off 30 psi at the gun. So by running, via the 1/2" hose to the caddy through the regulator/water trap and to the gun on the 3/8" (which gives me the flexibility of the smaller hose) I need to set the regulator to 105 psi approx to end up with the manufacturer recommend 90 psi at the gun. On the very infrequent occasion when i might run into something "supertight" I can just plug straight into the 12" hose and let "The Hooligan" loose.

Sorry folks, just noticed I said the Dakota is direct drive. Of course it's belt driven.

Excellent write.up.

Thanks Jock.

I have a mega noisy piston compressor..

Total contrast to the
'Fridge motor' Bambi I had before.

But the Bambi was just good for dusting.. silently.

Whereas to Biggun can inflate 4 car tyres on a charge.

Pugglt Auld Jock said:

<SNIP>

It's advertised as suitable to run on a 13amp supply. Well yes it does BUT, only if it's a fused supply. My garage is on an RCD, the house is fused, it trips the RCD every time but runs happily for hours on the socket in the utility room. My friend's son (electrician) has explained it's all to do with the Capacitive starter. He also says it probably just about blows the fuse each time it starts but will only pull about half that when running. He's going to wire in a "proper" supply for me when he's not busy but it's been running like this, on an occasional use basis for a couple of years now.


<SNIP>

.

Click to expand...

Hi,
Great post. on your tripping issue.

Is it a RCD (earth fault protection only) or RCBO (earth fault and overload protection) tht it's tripping? I assume it is tripping everthing off not just the one crcuit. If it is an RCD the compressor should not trip it unless it has an earth fault. If it is a RCBO (or is just tripping a single circuit i.e a MCB) the RCBO needs to be changed to a type "C" or "D" inrush rated one. see https://thegrid.rexel.com/en-us/for...een-type-b-c-and-d-miniature-circuit-breakers

The same type letters apply to RCBOs.
There are some considerations or cable size and loop impedance to take into account when changing but not normally an issue.

Robert G8RPI.

Hi Robert, thanks for that.

Just going supermarket shopping so no time now
Don't know about most of which you speak here. The garage has a 2.5 cable supply (much thicker than light wiring (Told the builder's electrician I wanted to be able to run my welder off it when the house was being built) off a 30amp fuse on the main board. it arrives in the garage to an isolating switch from which both the lights and single 13amp socket are wired. The socket is a single 13amp device with a red neon and a 2 buttons. One is labeled off/test the other on/reset. It's label says:- Type Ho8 RCCB.

Mrs J is calling - got to go - I'll check back later this afternoon.

PS. Have used my SIP 140 stick welder and my Mig off it for many years without any problems

Pugglt Auld Jock said:

Hi Robert, thanks for that.

Just going supermarket shopping so no time now
Don't know about most of which you speak here. The garage has a 2.5 cable supply (much thicker than light wiring (Told the builder's electrician I wanted to be able to run my welder off it when the house was being built) off a 30amp fuse on the main board. it arrives in the garage to an isolating switch from which both the lights and single 13amp socket are wired. The socket is a single 13amp device with a red neon and a 2 buttons. One is labeled off/test the other on/reset. It's label says:- Type Ho8 RCCB.

Mrs J is calling - got to go - I'll check back later this afternoon.

PS. Have used my SIP 140 stick welder and my Mig off it for many years without any problems

Click to expand...

Been doing a bit of follow up to what I wrote here. The wire going to the ceiling light is small diameter (I believe standard lighting twin and earth of 1.5mm?). I actually stripped out the single pendant fitted by the builders and put a flourescent at each end of the garage. The socket has thicker wire which I presume is 2.5mm? I just took the cover off the isolating switch unit and found two interesting things. There is a fuse, marked, to my surprise, 15amp? which would kill all power to the garage if it blew and the wire coming through the wall from the main fusebox in the house, although difficult to see clearly, looks to be slightly thicker!? The house was built just over 35 years ago. The main distribution board is fused - No circuit breakers - but the garage has the "stand alone" 13 amp RCD socket.

Having re-read what I wrote specifically about the Wolf Dakota above I feel it came across as me settling for a very much cost compromised choice. There was certainly an element of that when I bought - in that I could not afford to spend any more dosh! However, having owned it for over two years now I'm pleased to say that I'm absolutely delighted with my purchase. Shortly after I bought it I found the large diameter pulley on the compressor itself was slightly buckled (didn't run "true") My guess, from some marks I found on it and crush marks I noticed on the packaging when unpacking it, would be that it suffered an impact whilst in transit to me. I 'phoned UKHS and was very pleasantly surprised when, the very pleasant chap who answered, immediately offered to send a new pulley FOC! When I expressed my delight he went on to say that there had been a small number of incidents of this happening and they had decided to just replace the pulleys when requested. How refreshing! He also said that in future if I needed spares they carry a wide range and I should just ring them.

So. - Very pleased indeed with my purchase and pleasantly surprised with the backup and future prospect for spares. I can't think of any situation I might face with which it could not cope. Giving serious thought to maybe buying more "stuff" from them instead of defaulting to Machine Mart!

Just a final word (in case someone else finds themselves needing to remove a compressor pulley like mine.) Initially I couldn't get the pulley off the shaft. The reason being that at first I didn't realise that the compressor shaft is tapered! The pulley was locked on rather like a tight track rod end. DON'T JUST HIT IT! - you'll either bend or break the shaft! The pulley is ally and the shaft steel so responds well to a bit of heat to expand it. My wee gas canister type torch (used mostly for plumbing) did the trick and the pulley just popped off.

Happy compressing to you all!
Jock

Jock.
You blew me away with that last bit..

varesecrazy said:

Jock.
You blew me away with that last bit..

Click to expand...

Aye. I suppose, if you think about it for a wee while ------

Hi,
If it is a socket with a built in RCD its probably got some kind of overload protection that trips on the normal inrush current of the compressor. It does sound like you need an upgrade to the wiring, but to get the compressor running you could fit a standard single switched socket next to the RCD one just for the compressor.

The ideal solution would be a new consumer unit (fusebox) in the house with a 20A MCB (class C) and 2.5mm steel wire armoured (SWA) cable feeding a small consumer unit in the garage. Few hundred pounds worth of work though.

Robert G8RPI.

Thanks Robert. I had wondered about the additional safety you get with an all RCD system but both my daughter and older boy get problems with them jumping out for no apparent reason. My youngest boy has an old miners (as in coal miners) cottage which is on fuses like mine and neither of us have any problems so I'm reluctant to change.

The garage is integral to my house and the main house fuse board is on the other side of the wall from the garage. The feed cable to the isolator switch in the garage is probably all of one foot long! I think if my pal's son can do a supply (maybe a "blue" 16amp?) on a fused spur only and swop the single RCD socket for a double then I'd be "sorted" I could see myself using the welders and compressor, one at a time of course, on the Blue supply leaving the RCD protected supply for angle grinder, drills, hot air guns, garden stuff (although most are IC powered) and so on.

I was recently doing the "good neighbour bit" by helping a young chap who lives in the flats opposite me to change a rear shocker on his very tidy 58 plate Mazda 2. He was struggling away in the layby outside the flats with some very basic tools and obviously going to do some damage to fixings. He brought the car over to my drive's end and stuck 2 wheels up on the pavement. He was very keen to do it himself so I lent him a nice deep socket, extension and 1/2" ratchet. He had the top mount off in no time (the top of the shocker rod mounts to an aluminium casting which is retained under the wheel arch by two 13mm bolts - The casting gets swapped to the new shocker). The bottom bolt turned out to be a rather different kettle of fish though. It's a large bolt - 17mm socket I think? he was wielding the tools - which goes through a metalastic type bush and screws into a captive thread in the end of the suspension beam. It reluctantly unscrewed by about a turn and a half and then jammed up. We'd already wire brushed the bits we could reach and squirted Plus Gas on it. My Air compressor was set up with my small diameter hose and tyre inflator with a female PCL connector to accept the inflator tool. My old Clarke gun has a PCL connector so we grabbed it first. The intention being to use the gun to wind the bolt to and fro/in and out a few times to slacken the thread. The bolt pretty much laughed at it! Then I disconnected the small diameter hose and connected up my large diameter hose and "The Hooligan" with his large bore euro connectors. The difference was immediate and the bolt was removed with just a few to and fros!

These are the two guns:



In fact I've now got a euro connector and oiler on the Clarke too which has made it more than adequate for doing wheel nuts etc so I can preserve the "Hooligan" for things that really need serious "persuading"

So, I thought I'd risk resurrecting this thread as I've just come across this video:



It demonstrates very clearly exactly the point I was making in the original post above about my own setup. In fact the compressor looks identical to mine. I wonder how many different brand names are selling it? Interesting how greatly the integral regulator interferes with air flow. You have to wonder why the manufacturer decided on such a poorly performing component when a lot of people are going to buy a nice big compressor like this specifically to drive their air tools - just as I did.